Set pipeline CI ref in before(:create)

This hook only sets the value of the attribute so having it in the after
hook means that the value is set on the model but it is not persisted to
the DB

spec/factories/ci/pipelines.rb

@@ -23,7 +23,7 @@ FactoryBot.define do
     factory :ci_pipeline do
       transient { ci_ref_presence { true } }
 
-      after(:build) do |pipeline, evaluator|
+      before(:create) do |pipeline, evaluator|
         pipeline.ensure_ci_ref! if evaluator.ci_ref_presence && pipeline.ci_ref_id.nil?
       end